EAL

HD: Food Security (2011)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To determine if participation in food assistance programs moderated the effect of food insecurity on overweight and depression among elders.

Inclusion Criteria:

Respondents of the Health Retirement Study (HRS)
- 1996, 1998, 2000 and 2002 waves
- >54 years old in 1996
Respondents of the Asset and Health Dynamics Among the Oldest Old (AHEAD) study
- 1995, 1998, 2000 and 2002 waves
- >71 years old in 1995.

Exclusion Criteria:

Those participants of the HRS and AHEAD studies who did not meet age inclusion criteria.

Description of Study Protocol:

Recruitment

This study used existing data from the HRS and AHEAD studies

Design

Cohort study, using data from four follow-up surveys from each study
- HRS: 1996, 1998, 2000, 2002
- AHEAD: 1995, 1998, 2000, 2002.

Intervention

Not applicable

Statistical Analysis

Multi-level linear regression analysis using three different models:
- Current: To examine the effect of current food insecurity (FIS) and the effect of its interaction with participation in food assistance programs (FAP) on current outcomes
- Lagged: To examine whether previous FIS was related to subsequent change of outcomes and whether there was an interaction effect of previous FIS and previous participation in FAP on subsequent change of outcomes
- Difference: To examine whether the change in FIS was related to the change of outcomes, and whether the effect of the change in FIS on the change of outcomes was modified by the change of participation in FAP.

Data Collection Summary:

Timing of Measurements

HRS: 1996, 1998, 2000, 2002
AHEAD: 1995, 1998, 2000, 2002.

Dependent Variables

Relative weight:
- BMI (kg/m²) calculated with self-reported weight and height
- Used as a continuous variable in linear regression analysis and as an overweight/non-overweight dichotomy in logistic regression analysis
  - <25kg/m²=non-overweight
  - ≥25kg/m²=overweight
Depression
- Assessed with eight-item version of the Center for Epidemiologic Studies-Depression (CES-D) scale (scores range from zero to eight)
- Greater than four equals depression.

Independent Variables

Food Insecurity (FIS)
- Modified questions from the US Household Food Security Survey Module
- Classified as FIS if respondent reported either of the following conditions existed in past two years:
  - Did not always have enough money to buy the food they need
  - Skipped meals or ate less than they felt they should because there was not enough food in the house
Participation in Food Assistance Programs (FAP)
- Participation=respondent received food stamps at any time in the past two years or currently received home-delivered meals.

Control Variables

Age
Gender
Ethnicity (white and non-white)
Martial status (married and living together, never married, and divorced/widowed)
Education (no formal education, less than high school, graduated from high school, some college, college degree, and post-college degree)
Smoking status (current smoker or non-smoker)
Income (sum of all income for all household members)
Physical functioning
- Six items of activities of daily living (ADL)
- Five items of instrumental activities of daily living (IADL)
Health conditions (number of chronic diseases ever diagnosed by a physician)
Social interaction (having good friends in the neighborhood or getting together with people for a chat or social visit).

Description of Actual Data Sample:

Initial N:
- HRS: 9,481
- AHEAD: 6,354
- Total: 15,835
Attrition (final N):
- HRS:
  - Dropout rate less than 3% at each wave
  - Death rate less than 3%
- AHEAD:
  - Dropout rate less than 4% at each wave
  - Death rate <13%
- No association between food insecurity and death in AHEAD
- Sampling attrition was considered ignorable
Mean Age, First Wave (years ± standard deviation):
- HRS: 60.8±4.2
- AHEAD: 79.6±5.8
Race/Ethnicity, First Wave (percent White):
- HRS: 81.2
- AHEAD: 87.4
Other relevant demographics:
- Depression score
  - HRS
    - 3.1 (wave 1)
    - 3.6 (wave 4)
  - AHEAD
    - 2.9 (wave 1)
    - 3.5 (wave 4)
- Percent Depressed
  - HRS
    - 26.0 (wave 1)
    - 39.4 (wave 4)
  - AHEAD
    - 21.0 (wave 1)
    - 33.3 (wave 4)
Anthropometrics:
- BMI
  - HRS
    - 27.3kg/m² (wave 1)
    - 27.6kg/m² (wave 4)
  - AHEAD
    - 25.1kg/m² (wave 1)
    - 24.9kg/m² (wave 4)
- Percent overweight
  - HRS
    - 65.8% (wave 1)
    - 67.9% (wave 4)
  - AHEAD
    - 46.4% (wave 1)
    - 44.6% (wave 4)
Location: US.

Summary of Results:

Key Findings

Relation of food insecurity to BMI:

FIS was not related to BMI among the HRS participants (see table); but in the lagged model, when HRS respondents were categorized into two groups based on BMI level (overweight or non-overweight), those with food insecurity in the overweight group had an increase in BMI (β=0.35, P<0.004) whereas those with food insecurity in the non-overweight group did not (β=0.06, P<0.564).

Among the AHEAD participants, current food-insecure elders had higher BMI than current food-secure elders by 0.19 unit of BMI (P<0.033). As elders became food insecure after being food secure, their BMI increased by a mean of 0.3 (P<0.025).

Relation of food insecurity to depression:

Among the HRS participants, current food-insecure elders had higher depression scores than food-secure elders (β=0.27, P<0.001). Previous food-insecure elders also had a greater change in depression score than previous food-secure elders by 0.16 (P<0.05). FIS was not related to depression among the AHEAD participants (see table).

Interactions between FIS and participation in FAP on BMI

For HRS participants, interactions between food insecurity and participation in FAP on BMI were not significant. For AHEAD participants, food insecurity was positively related to BMI among nonparticipants in the Food Stamp Program for the lagged model (β=0.47, P=0.043), but was not related to BMI among participants.

Interactions between FIS and participation in FAP on Depression

For HRS participants, food insecurity and Food Stamp Program participation influenced the occurrence of depression symptoms in the current model. Food insecurity was positively associated with depression among non-participants of the program but not among participants (β=0.33, P=0.004). For AHEAD participants, interactions between food insecurity and participation in FAP on depression were not significant.

	Effect of FIS on BMI		Interaction effect of FIS and participation in Food Stamp Program on BMI			Interaction effect of FIS and Participation in home-delivered meals on BMI
	β	P-value	β for NP	β for PP	P-value	β for NP	β for PP	P-value
HRS (N=9,481)
Current model	-0.13	0.200	-0.07	-0.34	0.234	-0.12	-0.82	0.277
Lagged model	0.05	0.640	0.20	0.15	0.814	0.13	0.14	0.169
Difference model	0.17	0.233	-0.20	-2.25	0.868	-0.18	-1.42	0.213
AHEAD (N=6,354)
Current model	0.19	0.033*	0.24	-0.14	0.091	0.18	0.34	0.588
Lagged model	0.16	0.092	0.47	-0.03	0.043*	0.15	0.04	0.796
Difference model	0.30	0.025*	0.40	0.24	0.732	0.22	0.68	0.253

*Statistically significant (P<0.05)

NP=non-participation in programs

P=participation in programs

	Effect of FIS on depression		Interaction effect of FIS and participation in Food Stamp Program on depression			Interaction effect of FIS and participation in home-delivered meals on depression
	β	P-value	β for NP	β for PP	P-value	β for NP	β for PP	P-value
HRS (N=9,481)
Current model	0.27	<0.001*	0.33	-0.01	0.004*	0.27	0.05	0.477
Lagged model	0.16	0.013*	0.15	0.11	0.822	0.14	0.13	0.974
Difference model	0.11	0.384	0.08	-0.13	0.511	1.39	-0.14	0.062
AHEAD (N=6,354)
Current model	0.18	0.051	0.01	0.06	0.727	0.04	0.07	0.873
Lagged model	0.15	0.185	0.20	0.15	0.925	0.04	0.15	0.761
Difference model	0.05	0.802	0.10	0.51	0.651	0.05	0.25	0.769

*Statistically significant (P<0.05)

NP=non-participation in programs

P=participation in programs

Author Conclusion:

Food insecurity was generally related to a greater relative weight in the oldest group of elders and greater depression among both groups of elders in this study. The relation of food insecurity with BMI and depression was modified by participation in FAP in some analysis. When food-insecure elders participated in FAP, in general, food insecurity did not appear to increase weight and depression.

Funding Source:

University/Hospital:

Dept of Preventive Medicine, Hanyang University; Dept of Health Promotion, Education, and Behavior, University of South Carolina

Reviewer Comments:

I believe the authors of this study have made a leap in some of their conclusions based on the data they provide. The conclusions I would draw are:

Among HRS participants (younger group of elders):

FIS is not associated with BMI
The relationship between FIS and BMI is not modified by (dependent on) participation in FAP
FIS is positively associated with depression in the current model and lagged model
The association between FIS and depression is dependent on participation in the Food Stamp Program (food insecurity is more strongly linked to depression among non-participants than participants) in the current model, but not in the lagged model
The association between FIS and depression is not dependent on participation in home-delivered meals.

Among AHEAD participants (oldest group of elders):

FIS is positively associated with BMI in the current model and difference model
The association between FIS and BMI in these two models is not dependent on participation in either FAP
Whereas FIS is not significantly associated with BMI in the lagged model, the interaction term is statistically significant, revealing that the association between FIS and BMI in the lagged model is dependent upon participation in the Food Stamp Program (food insecurity is more strongly linked to BMI among non-participants than participants)
The association between FIS and BMI is not dependent on participation in home-delivered meals
FIS is not associated with depression.

Basically, with the exception of one out of six models, the relationship between FIS and BMI was not moderated by participation in FAP. With the exception of one out of six models, the relationship between FIS and depression was not moderated by participation in FAP.

I was unable to assign a favorable rating to #6 in the quality rating checklist because of the way participation in FAP was measured—whether a respondent received food stamps at any time in the past two years or receiving home-delivered meals currently. I believe the actual time being on FAP ("exposure") could have varied greatly in the two-year period, which may have affected the results. Families or other programs (e.g. faith-based programs) may have also provided food or meals for participants, which would not have been captured by this measure.

Quality Criteria Checklist: Primary Research
Relevance Questions
	1.	Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies)	Yes
	2.	Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about?	Yes
	3.	Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice?	Yes
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	Yes
2.	Was the selection of study subjects/patients free from bias?		Yes
	2.1.	Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	Yes
3.	Were study groups comparable?		Yes
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	N/A
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	???
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	N/A
	3.4.	If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis?	Yes
	3.5.	If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.)	N/A
	3.6.	If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")?	N/A
4.	Was method of handling withdrawals described?		Yes
	4.1.	Were follow-up methods described and the same for all groups?	Yes
	4.2.	Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.)	Yes
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	???
	4.5.	If diagnostic test, was decision to perform reference test not dependent on results of test under study?	N/A
5.	Was blinding used to prevent introduction of bias?		No
	5.1.	In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?	N/A
	5.2.	Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.)	No
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	No
	5.4.	In case control study, was case definition explicit and case ascertainment not influenced by exposure status?	N/A
	5.5.	In diagnostic study, were test results blinded to patient history and other test results?	N/A
6.	Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described?		No
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	N/A
	6.2.	In observational study, were interventions, study settings, and clinicians/provider described?	N/A
	6.3.	Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect?	???
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	No
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	No
	6.6.	Were extra or unplanned treatments described?	No
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	Yes
	6.8.	In diagnostic study, were details of test administration and replication sufficient?	N/A
7.	Were outcomes clearly defined and the measurements valid and reliable?		Yes
	7.1.	Were primary and secondary endpoints described and relevant to the question?	Yes
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	Yes
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	Yes
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	???
	7.5.	Was the measurement of effect at an appropriate level of precision?	Yes
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	No
	7.7.	Were the measurements conducted consistently across groups?	Yes
8.	Was the statistical analysis appropriate for the study design and type of outcome indicators?		N/A
	8.1.	Were statistical analyses adequately described and the results reported appropriately?	???
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	8.4.	Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)?	N/A
	8.5.	Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?	Yes
	8.6.	Was clinical significance as well as statistical significance reported?	No
	8.7.	If negative findings, was a power calculation reported to address type 2 error?	N/A
9.	Are conclusions supported by results with biases and limitations taken into consideration?		No
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes